European shares trade cautiously after Wall Street's record high

* STOXX 600 flat

* U.S. Futures slightly lower on political risk

* Belgium's Argenx jumps on Abbie (Adds quotes, shares)

By Julien Ponthus

LONDON, Aug 22 (Reuters) - European stock markets were broadly flat in mid-morning trade on Wednesday, showing more caution than Wall Street, where the benchmark S&P 500 reached a record high in its longest-ever bull-market run.

At 0830 GMT, the pan-European STOXX 600 was down 0.04 percent at 384 points, with no trend evident as investors waited to see whether the United States and China could make progress towards resolving their trade conflict.

Political developments in the United States have had limited effects, at least so far. U.S. President Donald Trump's former lawyer, Michael Cohen, pleaded guilty to campaign finance violations on Tuesday as former campaign manager, Paul Manafort, was found guilty on charges of tax and bank fraud.

"Overnight, U.S. equity futures eased back in tandem with a softening US dollar with a new and stronger political risk factor at work", said Neil Wilson, an analyst for Markets.com.

The moves are nevertheless quite modest with the futures for Wall Street's three main indexes down about 0.2 percent.

Shares (Berlin: DI6.BE - news) in Belgian biopharma Argenx posted the best performance of the STOXX 600, up 6 percent after Abbvie (Euronext: ABBV.NX - news) exercised an option to develop and commercialize a drug.

Among smaller companies, Adyen, the Dutch company which processes payments for Netflix (Xetra: 552484 - news) and Facebook (NasdaqGS: FB - news) , reported H1 profit up 75 percent and jumped 4.3 percent.

Denmark's Jyske Bank (LSE: 0MGD.L - news) was the worst performer, down 4.8 percent after it published its results for the second quarter.

Kaz Minerals (LSE: KAZ.L - news) lost 4.5 percent after publishing its first-half trading update.

Atlantia (LSE: 0I2R.L - news) rose 1.2 percent. Italian state lender Cassa Depositi e Prestiti (CDP) may buy a controlling stake in Autostrade (Milan: ATL.MI - news) per l'Italia, two sources told Reuters, while some members of the anti-establishment government have suggested that the motorway network should be nationalized after the disaster that killed 43 people. Vodafone rose 0.3 percent after Australia's TPG Telecom (Dusseldorf: YST.DU - news) said it was looking into a merger deal.

Linde (IOB: 0H3X.IL - news) dipped 0.2 percent after warning that divestments needed to secure approval for its planned tie-up with Praxair had a size that would allow either party to abandon the deal.

The industrial gases supplier nevertheless added that it was in constructive talks to salvage the $83 billion merger. (Editing by Larry King and Andrew Heavens)